Knitting of tubular articles on circular knitting machines



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KNITTING OF TUBULAR ARTICLES ON CIRCULAR KNITTING MACHINES Filed Oct. 20. I965 3 Sheets-Sheet s nos 3 I04 5 I03 3 27 I I FIG 6 United States Patent 3,492,837 KNITTING 0F TUBULAR ARTICLES 0N CIRtCULAR KNITTING MACHINES Tom Leslie Mountain, Leicester, England, assignor to The Bentley Engineering Company Limited, Leicester, England, a British company Filed Oct. 20, 1965, Ser. No. 498,398 Claims priority, application Great Britain, June 28, 1965, 27,211/ 65 Int. Cl. D04b /06, 15/24, 35/34 US. Cl. 66-107 4 Claims ABSTRACT OF THE DISCLOSURE A procedure and means for knitting a succession of tubular articles on circular knitting machines by which each. article is pressed off from the needles upon its completion and a fresh course to start a succeeding article is commenced during the pressing off of the preceding article while a portion of the yarn temporarily joins the completed article and the succeeding article, such joining portion of the yarn being severed before pressing off of the preceding article has been completed. The particular cutting means employed comprises a cutting device associated with at least one sinker in a sinker bed associated with a small group of needles and a sinker operating means arranged to cause the sinkers to cooperate with the small group of needles and the cutting device to engage the portion of yarn laid across the stems of the needles.

This invention is for improvements in or relating to the knitting of tubular articles on circular knitting machines and is concerned with a development of the invention described in the co-pending US. patent application of Roland Peberdy Ser. No. 496,007 filed Oct. 14, 1965. That invention refers to a simple and effective procedure for the production of a succession of knitted tubular articles, and the present invention has for an object to provide a procedure of this kind in which the articles produced in succession are separated from one another in a particularly effective manner. The invention in common with the earlier invention may be applied conveniently in use to circular knitting machines and especially to machines of the opposed co-axial needle cylinder type.

In common with the earlier invention the present invention is concerned with a method of knitting a succession of tubular articles on a circular knitting machine according to which each article on completion is pressed off from the needles, and before its pressing off is completed the setting up of a fresh course is commenced to start the next succeeding article with the yarn temporarily connecting the articles together, and during the pressing off of the preceding article the yarn joining it to the succeeding article is severed to separate the articles from one another. In practising the earlier invention the procedure described in said earlier specification involves subjecting the yarn to local strain to fracture it so as to separate the articles from one another, such subjection to local strain being conveniently effected 'by causing an elongation of the path of the yarn so as to burst it. In practising the present invention the yarn between successive articles is severed at the appropriate time by means of a cutting device. This is a particularly, useful way of severing a stretch yarn which is not easily burst by elongation of its path, but the cutting procedure can of course be used with any yarn.

An important advantage of the procedure of forming articles in succession and separating the articles after commencing the setting up of a fresh course for a succeeding article is that the yarn feeder can be maintained in feeding position during transition from one article to the next, thereby obviating the need to take any special steps to cause a free yarn end to become taken by needles which are devoid of stitches. The yarn held by the last needle to knit it is merely laid across the stems of a group of succeeding needles to provide a suflicient length of joining yarn and laid into the hooks of empty needles following said group of needles and such following needles can immediately commence to form the initial course of the new article. After such initial course has been commenced the yarn which extended across the stems of the group of needles is severed to separate the articles.

The invention further provides, in a circular knitting machine organised to knit a succession of tubular articles and having means arranged to press off each article as it is completed, means for feeding the yarn extending from the end of a completed article into the hooks of needles from which the fabric has been pressed off to commence setting up a new course before the preceding article has been fully pressed ed the needles, and means whereby, after the preceding article has been completed and the new course started, the yarn extending from the preceding article to the succeeding article is severed by cutting it to separate the articles.

A convenient form of cutting device for use in practising the present invention and its relation to parts of a circular knitting machine are illustrated by way of example in the accompanying drawings and will now be described with reference to the drawings in which:

FIGURE 1 is an elevation view in central cross section showing parts of top and bottom needle cylinders of a circular knitting machine and related parts with a thread cutting device in an inoperative position,

FIGURE 2 is a front view of a slider provided with a sinker blufiing projection,

FIGURE 3 is a view of part of the mechanism as shown in FIGURE 1 but with the thread cutting device in the operative position;

FIGURE 4 is a view of the cutting instrument and cutting edge;

FIGURE 5 is an enlarged detail elevation view in central cross-section of portions of the needle cylinders of the machine showing an article about to be pressed off and the commencement of knitting a succeeding article, and

FIGURE 6 is a developed view of a cam layout employed in the cam system of the machine being a machine having two yarn feeding stations.

While the application of the invention to an opposed needle cylinder circular knitting machine is shown by way of example, the invention is not limited in this respect.

The present improvements are shown as applied to a circular knitting machine constructed and operating as regards its needle and sinker control systems, exactly as described in said co-pending US. application of Roland Peberdy. Reference is directed thereto for fuller details of the machine, construction and operation.

The top and bottom needle cylinders are shown at 201 and 202 in FIG. 1 and they have vertical tricks or slots 203 provided in their outer surface to house sliders 204 and 205 through which needles such as 206 are operated to form tubular knitted fabric. The needles are of the well known double-ended type, transferable from one cylinder to the other for the knitting of plain or rib stitches as desired. Between each adjacent pair of needles a sinker 207 is provided. The sinkers are mounted for radial movement in tricks 208 cut in a ring 209 which is 3 located in the top of the needle cylinder 202. The sinkers are each provided with a nib 210 and serve to knockover the stitches formed by the needles and urge the knitted loops clear of the needles, and is well known.

It is common practice to provide adjacent to certain of the sinkers a masking device known as a sinker bluff. This device is housed in the same trick as the sinker with which it co-operates and normally lies in a low inactive position until required. It is activated by a projection such as 211 formed on the adjacent slider 205 (FIG. 2) and serves, when raised by the projection to cover the nib of the sinker so that unknitted lengths of yarn issuing from a feeder during reciprocatory knitting will not become undesirably engaged by the sinker nib. An adaption of this masking device in a modified form is used as part of the means in accordance with the present invention for positively severing the yarn joining successive knitted articles as aforesaid.

Following knitting of the toe pouch of the blank 34 by the normal procedure of reciprocatory knitting, complete circular courses of plain fabric are knitted at the main feed to provide in known matter unravelling courses which will afterwards be removed following closing of the toe end as by linking. On reaching the point where the next sock is to commence the back feed bolt cam shown at 101 (FIG. 6) is introduced to engage a small group of medium butt sliders 27 (being in the example shown the seven carrying the needles 28b) which are situated in the middle of the short knitting butts in the bottom cylinder. The knitting butts of the bottom sliders 27 are arranged in conventional manner i.e. short butts in the heel half and long butts in the instep half. As the group of medium butt sliders 27 pass down the bolt cam 101 the cam moves right in so that all following sliders will be lowered. It remains in for one cylinder revolution only and as no yarn is being fed at the back feed, the needles will all be pressed off as their sliders engage this cam. Continuing from the stage where the group of medium butt sliders have passed down the earn 101 they now proceed below cam 102 until their transfer butts encounter cam 103. They are then lifted by this cam so that their knitting butts ride up cam 104 and raise their needles to clearing height. As there is no yarn on these needles at this stage it is necessary to open the latches by other means and in this example the upper cylinder sliders indicated at 36 in FIG. 6 are directed to a level where their noses shown at 105 (which are formed with chisel ends suitably shaped for the purpose) encounter the needles whose sliders are progressing up the cam 104 and, by engagement of their chisel ends between the latches and hooks of the needles, open their latches.

The empty needles, led by the group 2812 whose sliders have medium butts continue at clearing height until they meet the needle lifter bolt cam 106 which is set to lift the medium butt group of sliders to a height above clearing height (being the height to which they are raised during the knitting of a heel pouch), while allowing the short butts to pass by it. The cam 106 is subsequently drawn right out to allow the long butts to pass by also at clearing height.

The state of affairs at this stage is as follows. Knitting of the final course of the finished sock is taking place at the main feed point A with sliders passing down the stitch cam 107. The sliders are then raised through the engagement of their transfer butts with cam 108 to raise the needles to clearing height as shown at 115 (and at 2811 in FIG. Needles are being pressed-off at cam 101 (as the needles to the left of group 28a move fully downwards) and latches of empty needles are being opened as sliders are being raised by cam 104. Empty needles are approaching the main feed point A at clearing height led by the group of seven or so needles (whose sliders have medium knitting butts) at heel height.

As the group of needles at heel height (281) in FIG.

5) pass by the main feed point A the yarn is laid by the feeder (shown at 37 in FIG. 5) from the last needle to knit prior to this group outside the stems of the group 28b at heel height and into the hooks of the following empty needles. The stretch of yarn laid outside the stems of the group of seven or so needles at heel height is a more or less straight length of yarn being. indicated at 38 in FIG. 5, and it is laid against the needle stems while the sinkers are out at the main feed point A.

The stretch of the yarn laid outside the stems of the group of seven or so needles at heel height is a more or less straight length of yarn and it is laid there while the sinkers are out at the main feed point. The sinkers are thrown out, as normally approximately between the places marked x1 and x2 in FIG. 6. It is at this stage that the alternative procedure of the present application is applied so that the length of yarn instead of being broken by the sinkers moving in to the knock-over position is caused otherwise to be severed as will now be described.

The sinkers adjacent to the group of seven or so needles at heel height are approximately situated in the middle of the short butt half circle of sliders whose needles would, when required, be capable of knitting by reciprocation. While a group of sinkers at each end of this half circle are provided with sinker bluffs, those in between the groups do not require bluffs. It is therefore possible to insert a bluff-like cutting instrument adjacent to at least one of the sinkers within the group of seven or so needles (and sliders) at heel height.

Such a cutting instrument (which may actually be formed from a sinker bluff) is shown at 212 in FIGS. 1 and 3. It is located in similar manner to a sinker bluff adjacent to a sinker and in the same trick and has a butt 213 which travels in the same cam track as the butt of the sinker itself. In the low inoperative position shown in FIGURE 1 it can move in and out with the sinker without interfering with the yarn. When however its adjacent slider, which is provided with a projection 211, is raised to heel height together with the others in the group of seven or so, the instrument 212 is raised by the projection 211 and its cutting edge shown at 212a assumes the position shown in FIGURE 3 the edge being in advance of the throat 210a of the sinker. As the sinkers move in to the knock-over position this cutting edge will contact the straight lengths of yarn laid across the group and will sever it positively by cutting it between the two adjacent needles.

Although because of the advanced position of the cutting edge in relation to the throat of the sinker, cutting of the yarn is quite possible if only one needle on each side of the instrument is raised, it is obvious that if more than one cutting instrument is provided and more than two needles raised, then the cutting action will be more severe and this could be an advantage when very elastic yarns are in use.

What I claim is:

1. In a circular knitting machine constructed to knit a succession of tubular articles, the combination comprising a needle cylinder, needles in said cylinder, cam means for operating said needles, yarn feeding means constructed to feed yarn to the needles and to continue such feed of the yarn from a preceding article to build a succeeding article, means for pressing off each article from the needles as it is completed, a sinker bed, sinkers in said bed, a cutting device associated with at least one of said sinkers associated with the small group of needles, and sinker operating means arranged to cause the sinkers cooperating with the small group of needles and said cutting device to engage the portion of yarn laid across the stems of said needles so that on completion of an article and after a commencement of a succeeding article the yarn is cut and the articles are severed.

2. A combination according to claim 1 comprising means for raising a small group of needles following the last ones holding a preceding article so that stems of such raised needles receive a portion of yarn in readiness for severance, and means mounting the cutting means for actuation to engage the yarn and cut it between adjacent ones of said raised needles.

3. A combination according to claim 2 wherein the cam means comprises a bolt cam to elfect raising of the small group of needles to receive the portion of yarn between the articles and butts associated with the needles in said small group for selective engagement by said bolt cam.

4. A combination according to claim 2 comprising an inside sinker ring mounted within the needle cylinder, inside sinkers mounted on said ring, a cutting device in the shape of a sinker blufi' associated with a sinker related to needles in said small group, and sinker cams organised to operate said cutting device and sinkers related to the small group of needles to move them inwardly when said needles are raised to engage with the portion of yarn against the needle stems and cause the cutting device to cut the yarn.

References Cited UNITED STATES PATENTS 1,285,096 11/1918 Fisher 66147 1,441,110 1/1923 OLena 6693 1,546,790 7/1925 OLena 66--93 1,691,887 11/ 1928 Matthews 66l07 1,870,550 8/1932 Bentley et al 6614 1,986,317 1/1935 Bentley et a1 6614 2,385,056 9/1945 Bromley et a1. 66l07 XR 2,398,785 4/ 1946 Grothey 66l07 3,402,575 9/ 1968 Peberdy 6614 XR W. CARTER REYNOLDS, Primary Examiner US. Cl. X.R. 66 47 

